Spectral energy distribution for NGC 4756: (blue) filled circles correspond to data from NED and Grützbauch et al. (2005a) in B and R bands. Arrows show upper limits; error bars indicate the band width and 3σ uncertainties. The continuous line (red) shows the predictions of our model (see text). Dust components (warm and cold with PAH, discussed in Mazzei et al. 1992) with the same average properties derived by Mazzei & De Zotti (1994) for a complete sample of nearby early-type galaxies are included (i.e. I₀ = 46   I_local, Iw = 200   I_local, R_wc = 0.27 and r_d = 100   r_c, see in Mazzei et al. 1994).